Electromagnetic relay



Jan. 27, 1942. T. R. RAYNER EIAL 2,270,966

ELECTROMAGNETIC RELAY Filed May 18, 1939 43 I "iii: W him IlO ' IVE-.5. I2 25 s 'N s N w vis :5

mvgn'ron THOMAS ROBERT RRYNER' MARING BY ZM & ATTORNEY Patented Jan. 27, 1942 ELECTROMAGNETIC RELAY Thomas Robert Rayner, Wallasey, and Aafko Oltman Maring, Liverpool, England, assignors to Associated Telephone & Telegraph Company, Chicago, 111., a corporation of Delaware Application May 18, 1939, Serial No. 274,386 In Great Britain May 31, 1938 4 Claims.

The present invention relates'to electromagnetic relays for use in light current electrical signalling and control systems and the like, and is more particularly concerned with relays of the so-called magnetic locking type, that is to say, relays which will remain held in an operated position by virtue of the provision of a permanent magnet. Such relays find particular application to systems for the centralised supervision of power transmission systems where, after the reception at a central station of a signal transmitted over a line from a remote station, it is desirable that the signal responsive device, which may be a relay of the above type, should maintain the position to which it has been set independently of the control battery supply so that failure of this supply will not result in the loss of the last signal indication received.

One type of relay which has found some degree of employment for this purpose is a modification of the Well-known horizontal relay as used in telephone or like systems, and is provided with a U-shaped permanent magnet fitted in place of the ordinary operating coil. This magnet has a small coil wound on each of its two limbs, the magnetic circuit being completed via the relay armature which co-operates with the ends of the limbs. The coils are connected in series across the line from the distant station to be supervised, and the connections are such that in response to a signal of one polarity the flux from the coils assists that from the permanent magnet so as to attract the armature and so operate the relay 'springset, the armature remaining at the end of the signal in an operated position due to the pull of the permanent magnet alone. On the subsequent reception of a signal of reverse polarity, a coil flux in the opposite direction to that from the permanent magnet is produced so that the relay now restores its armature. At the end of this signal the load on the springset maintains the armature in its normal position against the pull of the permanent magnet.

This type of relay has certain disadvantages inherent in its design which may be set out as follows. Firstly, the springset load must be heavy enough to prevent operation of the relay by the pull of the permanent magnet alone and yet must not be so heavy that the relay will hold unsatisfactorilyin its operated position. Secondly, each signal of reverse polarity tends to demagnetise the permanent magnet so that arrangements must be made to ensure that the signals do not exceed a predetermined current value and that they will never be maintained for any long period.

Thirdly, with the armature in its normal position there is a very large leakage flux so that relays cannot ,be mounted adjacent to one another on account of interference between them. It is the chief object of the invention to provide an improved relay performing the functions mentioned in which the disadvantages enumerated above are satisfactorily overcome.

According to one feature of the invention in an electromagnetic relay of the two-position polarised type the armature is moved to one position by current through the single operating coil in one direction and to the other position by current through the operating coil in the other direction, the armature being maintained in each position after the operating current ceases by the magnetic action of a single permanent magnet.

According to another feature of the invention in an electromagnetic relay of the two-position polarised type arranged to be operated to its respective different positions by currents in opposite direction through its operating winding, the parts are so disposed that the effect of the energisation of the winding is to direct the flux from a permanent magnet through one or other of two magnetic circuits, the movement of the armature thereby produced altering the reluctance of the said circuits so that when the winding is no longer energised the flux from the magnet continues to flow over the same circuit and thereby retains the armature in the position to which it has been set.

A further feature of the invention is that in an electromagnetic relay of the two-position polarised type, the armature is included in a magnetic circuit including a permanent magnet, the core on which the operating coil is wound forming a shunt across the armature portion of the circuit so that when the coil is energized in one direction only a small flux passes through the shunt circuit and the armature is attracted, while when the coil is energised in the opposite direction a considerable flux passes through the shunt circuit and is effective to bring about the attraction of an auxiliary armature which is linked to the main armature and in operating restores it to its unattracted position.

The invention will be better understood from the following description of one method of carrying it into effect, reference being had to the accompanying drawing comprising Figs. 1-5. This shows various views of a modified relay of the horizontal type, Fig. 1 showing a plan view of the relay with the armature removed so as to show the air gap provided around the polepiece of the operating winding of the relay, the armature being shown separately in Fig. 2. In Fig. 3 is shown a side view of the relay, while Figs. 4 and 5 show in diagrammatic form side views of the relay with its armature in the normal and operated positions respectively.

It will be seen from Fig. 3 that the relay comprises essentially a main L-shaped yoke or heelpiece II) on which is mounted the springset II and to one end of which the armature mounting bracket 9 of magnetic material carrying the pivoted armature I2 is secured by the screws 28 and 29 (shown for convenience in Fig. 2). An alloy block magnet I3 is clamped between the subsidiary yoke I4 and the main yoke I0, the fixing screws I5 and I6 passing through the magnet and threading into the heelpiece ID. An operating coil I1 is secured by a screw I8 to the yoke I4 the polepiece I9 of this winding projecting as shown in Fig. 1 into a hole provided in the heelpiece I0, so as to leave a suitable annular airgap between the polepiece and the heelpiece. The connections to the coil are led out through slots in the magnet I3 to suitable wiring terminals as shown in Fig. 3. The armature I2 is of the well-known standard pivoted type which is modified by affixing to it by means of the screw a right-angled link bracket 2I of non-magnetic material at the other end of which is fixed a circular plate 22 by means of screw 23, this plate being concentric with the polepiece I9 of the magnet II. The attraction of the plate 22 towards the polepiece of the magnet I! will therefore cause the armature to move its extension limb 24 away from the springset and so restore this to normal, while the operation of the armature proper I2 in the normal manner towards the polepiece 25 of the yoke I4 causes the springset to be operated. For the purpose of adjusting the minimum air gap between the armature and polepiece 25 and the armature plate 22 and the heelpiece Ill, the residual adjusting screws 26 and 21 respectively are provided.

Referring now to the diagrammatic views Figs. 4 and 5 which will serve for explaining the functioning of the relay, the block magnet which is preferably of aluminium nickel-cobalt alloy, is magnetised across its width as indicated by the polarity markings shown. Hence with the armature in the unoperated position as shown in Fig. 4, the major part of the magnet flux will extend up the yoke I4, through the core 30 of the operating coil I1, the plate 22 and back via the heelpiece Il]. A small flux will also extend via the polepiece 25, the air gap and the armature I2 and so tend to operate the armature, but due to the large reluctance of this path compared with that of the other path available, the pull on the armature I2 will be negligible compared with that on the plate 22 and the armature will therefore lock in its normal position.

Assuming now that a signal is received of such nature as to operate the relay, the coil I! will magnetise its core 30 in the same direction as the permanent magnet I3, that is, the left-hand end thereof as indicated, in the drawing, will become the south pole corresponding to the poles indicated for the permanent magnet. The effect produced now will be that the fiux from the permanent magnet I3 will not be able to circulate via the core 30 since this is magnetised in opposition thereto and the combined fluxes of the coil core and magnet will extend via the yoke I4, polepiece 25 to the armature I2 and return down the heelpiece I0. Under these conditions the pull on the armature I2 will be much greater than that on the plate 22 so that the armature will move to the polepiece 25 and operate the springset.

At the end of the signal the comparatively large gap between the plate 22 and the heelpiece I0 will ensure that practically the whole of the magnet flux will maintain a path via the yoke II, polepiece 25, armature I2 and then back via the heelpiece I0 so that the armature will remain locked in its operated position as shown in Fig. 5.

On the reception of a further signal to restore the relay to normal, the coil I! will magnetise the core in the opposite direction to the permanent magnet l3 with the south pole at the right hand end thereof as shown in the drawing so that an opposition flux to that of the permanent magnet will extend via the armature I2 and polepiece 25. The pull on the armature will now be reduced to a low value but the fluxes are in the same direction as regards the plate 22 and the pull on this combined with the springset load will restore the armature to the normal position of Fig. 4.

After the cessation of the signal the magnet flux will circulate as before in a local circuit via the yoke I4, core 30, polepiece I9, plate 22 and heelpiece I0 so as to lock the relay in its normal position.

We claim:

1. A two position polarized relay comprising a pair of parallel magnetic members, a permanent magnet in bridge of said members at one end thereof, an air gap between the other ends of said members, an electromagnet nearly in bridge of said members at a point between said air gap and said permanent magnet in parallel with the permanent magnet, an armature pivotally mounted on one of said members and bridging said air gap when in operated position, a second air gap between the core of said electromagnet and said one member, a second armature rigidly secured to said first armature and bridging said second air gap when in operated position, the flow of magnetic flux in one direction through the core of said magnet causing attraction of said first armature to close the first air gap, and the fiow of flux through the core in another direction causing attraction of said second armature to thereby retract said first armature and close said second air gap.

2. In a two position polarized relay, a pair of magnetic yokes, a parmanent magnet rigidly secured at each end to one of said yokes, an armature operable to bridge an air gap between the ends of said yokes opposite the permanent magnet, an electromagnet mounted on one of said yokes and having its core extending toward the other yoke, a second air gap in said other yoke surrounding one end of the core of said electromagnet, an auxiliary armature rigid with the first armature and operable to bridge said second air gap, current in one direction in said electromagnet causing attraction of said first armature and current in the other direction in said electromagnet causing attraction of said auxiliary armature, the normal flux in said permanent magnet retaining either armature attracted.

3. A two position polarized relay comprising a pair of magnetic yoke members, a permanent magnet mounted with each end secured to one end of said members, the other ends of said members spaced apart to form an air gap, an armature operable to bridge said air gap, an electromagnet mounted on one of said yoke members,

and a second air gap between the end of the core of said electromagnet and said other yoke member, energization of said electromagnet by current in one direction causing flux to flow through the magnets in parallel to attract said first armature and energization of said electromagnet by current in the other direction causing flux to flow through the magnets in series to attract said second armature and caus retraction of said first armature.

4..A.PQ1&X1ZB.Q,L 1Y comprising parallel magnetic yokes, mmanent magnet bar and an electromagnet mounted betWefi said yokes with the core of the electro-magnet in parallel with parallel to said permanent magnet, between the permanent magnet and the air gap, a second armature rigidly secured to said first armature the permanent magnet bar and adjacent thereto, the ends of said yokes adjacent the electromagnet forming an air gap, agarmature operable to bridge said gap, one end 6fth'core of said electromagnet and one of said yokes spaced apart to form a second air gap, a second 3 mm. ture rigidly secured to said first armature and mounted to bridge said second gap, the energization of said electromagnet by current in one direction causing attraction of the first armature to close the first air gap, and the energization of said electromagnet by current in the opposite direction causing attraction of the second armature to close the second air gap and thereby re- 15 tract said first armature.

THOMAS ROBERT RAYNER. AAFKO OLTMAN MARING. 

